36.6 Mail-Composition Methods

In this chapter we have described the usual Emacs mode for editing
and sending mail—Mail mode. Emacs has alternative facilities for
editing and sending mail, including
MH-E and Message mode, not documented in this manual.
See (mh-e)Top section `MH-E' in The Emacs Interface to MH. See (message)Top section `Message' in Message Manual. You can choose any of them as your preferred method.
The commands C-x m, C-x 4 m and C-x 5 m use
whichever agent you have specified, as do various other Emacs commands
and facilities that send mail.

If you select a different mail-composition method, the information
in this chapter about the ‘*mail*’ buffer and Mail mode does not
apply; the other methods use a different format of text in a different
buffer, and their commands are different as well.